Multiple control system and method of manufacture thereof



Nov. 28, 1967 E, G. TRONCA 3,355,628

MULTIPLE CONTROL SYSTEM AND METHOD OF MANUFACTURE THEREOF Filed Aug. 26, 1965 I? Md f j United States Patent 3,355,628 MULTIPLE CONTROL SYSTEM AND METHOD OF MANUFACTURE THEREOF Edward George Trouca, Milwaukee, Wis., assignor to Globe-Union Inc., Milwaukee, Wis., a corporation of Delaware Filed Aug. 26, 1965, Ser. No. 482,859 11 Claims. (Cl. 317-99) The present invention relates in general to multiple control systems and, more specifically, to electrical control systems including a plurality of tandem mounted control devices which are concurrently controlled by a single shaft and to the method of manufacturing such control systems.

In many present-day electrical and electronic applications, such as in stereophonic audio reproduction systems, multiple controllers or control systems are employed wherein a plurality of control devices, such as potentiometers, are mounted in tandem and are to be concurrently controlled by a single control shaft. Such control devices must be electrically matched in order to provide the desired multiple operation when controlled by a single control shaft. Various techniques are presently used in the matching of tandem mounted components such as potentiometers. In one technique, the resistance elements of the potentiometers are selected from the same batch or are formed from the same resistance strip. In a second technique, the overall resistances of resistance elements used in such otentiometers are measured and, if the resistances of the elements are substantially equal, the elements are assumed to have the same electrical characteristics and 'are employed in the tandem mounted potentiometers. In a third technique, the sloppiness in the mechanical fit between adjacent mounted control devices, such as potentiometers, is utilized and the control devices are offset relative to one another to provide the desired electrical matching. Such techniques have not proved to be entirely satisfactory and consequently it has been desirable to provide an improved multiple control system and improved method of manufacture thereof.

In accordance with the primary object of the present invention, a new and improved multiple control system is provided. More specifically, a new and improved electrical control system is provided which includes a plurality of tandem mounted control devices which are concurrently controlled by a single control shaft. In this connection, it is an object to provide a new and improved method of manufacturing such control systems.

A further object of the present invention is to provide a new and improved control system including a plurality of tandem mounted control devices which are concurrently controlled by a single shaft wherein the shaft is provided with a corresponding plurality of control portions and the shaft is formed so that the control portions may be offset relative to one another to match the control devices. Moreover, it is an object to provide a new and improved control shaft for use in multiple control systems. In this latter connection, it is an object to provide a new and improved control shaft having a plurality of control portions wherein the shaft is formed so that the control portions may be offset relative to one another.

A general object of the present invention is to provide a new and improved multiple control system, characterized in its simplicity and economy, which may readily be modified. A related object is to provide a new and improved control shaft for such a control system, likewise characterized in its simplicity and economy, which may readily be modified.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description taken in conjunction with the drawing.

In one form of the present invention, a multiple control system is provided which includes a plurality of control devices mounted in tandem, the control devices having rotatable control elements and having apertures extending therethrough which are aligned. A shaft is provided which extends through the apertures and the shaft is formed with control portions which are keyed to and controllably engage the rotatable control elements so that the control elements are rotated concurrently with the shaft. The shaft is formed so that adjacent control portions thereof may be twisted relative to one another to offset the control portions relative to one another to match adjacent control devices. The invention also resides in the method of manufacturing such a multiple control system.

The present invention will now 'be described with reference to the drawing wherein:

FIGURE 1 is a sectional side elevational view of a multiple control system constructed in accordance with the teachings of the present invention;

FIGURE 2 is a view showing facing surfaces of a portion of the system shown in FIG. 1; 1

FIGURE 3 is a side view of a control shaft utilized in the system of FIG. 1 which is constructed in accordance with the teachings of the present invention; and

FIGURE 4 is a partial perspective view of the control shaft shown in FIG. 3 showing control portions thereof in offset positions.

While the invention has been shown and will be described in some detail with reference to a particular, exemplary embodiment thereof, there is no intention that it be limited to such detail. Quite to the contrary, it is intended here to embrace all the modifications, alternatives and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

Referring now to the drawing and more specifically to FIG. 1, a multiple control system 10 is shown which is constructed in accordance with the teachings of the present invention. As may be seen, the exemplary control system 10 includes a pair of control devices 11 and 12 which are mounted in tandem, i.e., are mounted in piggy-back fashion, and which are disclosed as potentiometers. However, it will be readily apparent that a greater plurality of control devices may be mounted in tandem and control devices other than potentiometers may be mounted in tandem. For the purpose of allowing the control devices 11 and 12 to be connected together in tandem, a mounting plate 13 is suitably secured to the control device 12, such as by soldering, and has tabs 13a extending therefrom that are received in apertures within the main housing 11a of the control device 11. The tabs 1311 are bent over as shown to secure the control devices 11 and 12 together.

Since the internal elements of the control devices 11 and 12 (FIGS. 1 and 2) are identical, corresponding numbers are given thereto. Each control device includes a terminal-resistance element assembly 14. The terminalresistance element assembly 14 includes (1) a disc-like main body portion 14a which is generally formed of a relatively rigid plastic material such as a fibrous sheet impregnated with phenolic and which has a central circular aperture 14a provided therein, (2) an annular conductive member 1412 formed on the main body portion 14a, is electrically connected to a terminal extending radially outwardly therefrom, and (3) an annular resistance element 14d which is electrically connected to a plurality of terminals 142 extending radially outwardly therefrom at spaced positions around the resistance element. For the purpose of completing an electrical circuit between the annular conductive member 14b and the resistance element 14d and thus for the purpose of completing an electrical circuit between terminal 140 and'terminals 142, each control device is provided with a nonconductive rotatable control element 14 having a spring-like wiper anm contact 14g mounted thereon for resiliently engaging the contact member 14b and a spring-like wiper arm contact 14h mounted thereon for rcsilientlyengaging the resistance element 14d, the wiper arm contacts 14g and 14h being integrally formed and thus electrically connected together. It will be apparent that, as the control element 14 of a control device is rotated, different resistances will be developed between terrhinal 14c and the terminals 14c. In order to limit the rotational movement of the control element 14 suitable stop means may be provided. Since the specific details of the control devices 11 and 12 do not constitute a portion of the present invention, further details thereof will not be set forth.

' In accordance with the present invention, new and improved means are provided for concurrently rotating the rotatable elements 14f and thus for concurrently varying the control devices 11 and 12. For this purpose, a shaft 20 (FIGS. 1, 3 and 4) is provided which, in the exemplary arrangement, includes a main body portion 20a and a pair of control portions 2% and 200. The shaft 20 is formed with a reduced diameter at position 20d intermediate the control portions 2% and 20c so that the control portions may be twisted relative to one another to offset positions as best seen in FIG. 4. As may be seen by reference to FIG. 1, the control portion 20b controllably or drivingly engages the control element 14 of the control device 11 because of the fiat sides thereof and the corresponding keyed aperture in the control element 14 so that the control element 14 rotates with the shaft 20 and the resistance between selected terminals of the control device 11 may be controllably varied by rotating the shaft 20 a desired amount. In like manner, the control portion 200 controllably or drivingly engages the control element 14 of the control device 12 so that the control element 14 rotates with the shaft 20 and the resistance between selected terminals of the control device 12 may be controllably varied by rotating the shaft 20 a desired amount. Thus, the control elements 14f of the control devices 11 and 12 are concurrently rotated and the control devices 11 and 12 concurrently vary as rotational movement'is imparted to the shaft 20. As mentioned hereinabove, in many applications, the multiple control devices must be electrically matched. For this purpose with the exemplary control system constructed in accordance the teachings of the present invention, the control portions 201) and 200 of the shaft 20 are twisted relative to one another to offset positions whereby the control devices 11 and 12 in the exemplary arrangement are electrically matched.

.' A brief description of the method of constructing the assembly as shown in FIG. 1 may be helpful in understanding the present invention. The shaft 20 is formed with amain body portion 2M and a pair of flat sided control portions 20b and 200 separated by an intermediate portion 20d of reduced diameter which allows for twisting the control portions relative to each other to offset positions. The control devices 11 and 12 are then assembled'on the shaft so that the shaft is received in aligned apertures extending therethrough and the control elements 14] of the respective control devices 11 and 12 are controllably or drivingly engaged by the control portions 20b and 20c of the shaft 20. The control assemblies 11 and 12 are connected together by inserting tabs 13a of the mounting plate 13 through apertures in the main housing 11a of the control device 11 and bending over the tabs 13a. For the purpose of locking the control devices 11 and 12 in place on the shaft 20, a lock'ring' 22 is positioned within a groove 20:; of the shaft 20, the lock ring engaging the control element 141 of control device 11. The control devices 11 and l lfare then electrically matched by rotating the control lement 14 of device 11. and the associ d co tr l portion 20b relative to the control element 14 of device 12 and the associated control portion 200 so that the shaft 20 is twisted or cold worked at position 20d and the control portions 20b and 29c are offset a prescribed amount relative to one another. As may be seen, the control portion 26c extends through an aperture 12a in the rear surface of the control device 12 so that the control portion 20c may be gripped by a suitable tool for a twisting operation. On the other hand, the control portion 20b is directly connected to main body portion 20a of the shaft 20 so that the main body portion may be gripped by a suitable tool for a twisting operation. Thus, suitable tools may be associated with the control portions for effectively grippingly engaging the control portions so that they may be twisted relative to one another to the electrically matched positions. After such a matching operation, a cap 12b may be suitably secured to the control device 12, such as by soldering, to cover the exposed portion of the control portion Zdc to act as a dust shield and to prevent undesirable access to the control portion 200. Alternatively, a switch may be suitably secured to the control device 12. Under such conditions, an appropriate opening is formed in the rear wall of the control device 12 and switch mechanisms are extended therethrough for engagement with appropriate actuator means formed on the control element 14 (not shown). Since the details of the cap 1% or switch do not constitute a portion of the present invention, further details thereof will not be set forth.

For the purpose of allowing for mounting of the assembly 10 on a panel or wall, a threaded mounting bushing 25 is suitably secured to the control device 11, the main body portion 20a of the shaft 20 extending through a corresponding bore 25a in the bushing. The portion 20a of the shaft 20 and the threaded portion of the bushing 25 may then be inserted through a corresponding aperture in a wall or panel and a nut may be threaded onto the threaded portion of the mounting bushing 25 to lock the assembly 10 in place on the panel or wall. The assembly 10 may then be controlled by imparting rotational movement to the shaft 2% so that the control devices 11 and 12 are concurrently varied.

In view of the foregoing, it will be apparent that a new and improved multiple control system has been provided which allows for matching a plurality of control devices which are concurrently varied or controlled. Moreover, it will be seen that a new and improved control shaft has been provided for use in connection with such a multiple control system. Finally, it will be seen that a new and improved method of manufacturing multiple control systems has been provided.

What is claimed is:

1. In a multiple control system, the combination which comprises a plurality of control devices mounted in tandem and having rotatable control elements, the control devices having apertures extending therethrough which are aligned and which define keyed apertures in the control elements, and a shaft extending through the apertures which is formed with control portions corresponding in number to the control devices for controllably engaging the keyed apertures of the rotatable control elements so that the elements are rotated concurrently with the shaft, said shaft including at least one portion between said control portions which is yieldable in torsion, means for angularly adjusting one portion of the shaft with respect to the other including portions at which said shaft may be engaged to enable said control portions to be rotated to permanently distort said portion.

2. In a multiple control system, the combination which comprises a plurality of electrical control devices mounted in tandem and having rotatable control elements, the control devices having apertures extending therethrough which define keyed apertures in the control elements, and a rotatable member extending through the apertures which is formed with control portions corresponding in number to the control devices for controllably engaging the keyed apertures of the control elements so that the control elements are all rotated concurrently with the rotatable member, said rotatable member including at least one portion between said control portions which is yieldable in torsion, means for angularly adjusting one portion of the shaft with respect to another, including portions at which said shaft may be engaged to enable said control portions to be rotated to permanently distort said yieldable portion.

3. In a multiple control system, the combination which comprises a pair of electrical control devices mounted in tandem and having rotatable control elements, the control devices having aligned apertures extending therethrough which define keyed apertures in the control elements, and a shaft extending through the apertures which is formed with a pair of control portions for controllably engaging the control elements so that the control elements are rotated concurrently with the shaft, said shaft including a portion between said control portions which is yieldable in torsion, means for angularly adjusting one portion of the shaft with respect to another portion, including portions at which said shaft may be engaged to enable said control portions to be rotated to permanently distor said yieldable portion.

4. In a multiple control system, the combination which comprises a plurality of electrical control devices mounted in tandem and having rotatable control elements, the control devices having aligned apertures extending therethrough which define keyed apertures in the control elements, a common shaft extending through the apertures which has a plurality of control portions corresponding in number to the control devices for controllably engaging the keyed apertures of the control elements so that the control elements are rotated concurrently with the shaft, the shaft including at least one portion between said control portions which is yieldable in torsion, means for angularly adjusting one portion of the shaft with respect to another portion, including portions at which said shaft may be engaged to enable said control portions to be rotated, and means for allowing at least one of the control portions to be grippingly engaged so that they may be twisted relative to one another.

5. In a multiple control system, the combination which comprises at least two electrical control devices mounted in tandem and having rotatable control elements, the control devices having apertures extending therethrough which define keyed apertures in the control elements, and a shaft extending through the apertures which is formed with control portions corresponding in number to the control devices for controllably engaging the keyed apertures of the control elements so that the control elements are rotated concurrently with the shaft, the shaft having a reduced diameter, yieldable in torsion, to permit permanent distortion of the shaft intermediate the control portions so that the control portions may be twisted to offset positions relative to each other to electrically match the control devices, and means for allowing the control portions to be effectively engaged so that they may be twisted relative to each other.

6. A shaft for concurrently controlling a plurality of control devices comprising a main body portion, a plurality of control portions for rigid attachment to parts of said control devices, and at least one portion between said control portions which is yieldable in torsion by twisting said control portions and means for permanently angularly displacing portions of the shaft.

7. The shaft claimed in claim 6 wherein said portion between said control portions has a thickness gradually decreasing from a maxi-mum at points nearest said control portions.

8. A multiple control system having a plurality of control elements each including first and second portions rotatable relative to one another, a shaft passing through said control elements, said shaft being rotatable relative to said first portions and being attached to said second portions whereby said second portions rotate with said shaft, at least one of the portions of said shaft intermediate said second portions being yieldable in torsion by a twisting action to permanently distort the shaft, means for twisting portions of said shaft to angularly displace said portions and permanently distort the shaft.

9. The multiple control system of claim 8 wherein said yieldable portion includes a portion of reduced thickness between said second portions whereby said attached portions may be rotated relative to one another by twisting said shaft about said portion of reduced thickness.

10. The multiple control system of claim 9 wherein said reduced thickness portion comprises a section having a thickness gradually decreasing from a maximum at points nearest said attached portions.

11. The multiple control system of claim 10 wherein the second portions are keyed to said shaft.

References Cited UNITED STATES PATENTS 2,401,037 5/1946 Arvin 338-l32 X 2,971,174 2/1961 Lyon 338l30 3,024,629 3/ 1962 Ra-skhodoff 64-24 3,100,883 8/1963 Blanco 338-131 X 3,238,319 3/1966 Godel et al 200l4 X FOREIGN PATENTS 691,281 5/1953 Great Britain.

ROBERT S. MACON, Primary Examiner. ROBERT K. SCHAEFER, Examiner.

M. GINSBURG, Assistant Examiner. 

3. IN A MULTIPLE CONTROL SYSTEM, THE COMBINATION WHICH COMPRISES A PAIR OF ELECTRICAL CONTROL DEVICES MOUNTED IN TANDEM AND HAVING ROTATABLE CONTROL ELEMENTS, THE CONTROL DEVICES HAVING ALIGNED APERTURES EXTENDING THERETHROUGH WHICH DEFINE KEYED APERTURES IN THE CONTROL ELEMENTS, AND A SHAFT EXTENDING THROUGH THE APERTURES WHICH IS FORMED WITH A PAIR OF CONTROL PORTIONS FOR CONTROLLABLY ENGAGING THE CONTROL ELEMENTS SO THAT THE CONTROL ELEMENTS ARE ROTATED CONCURRENTLY WITH THE SHAFT, SAID SHAFT INCLUDING A PORTION BETWEEN SAID CONTROL PORTIONS WHICH IS YIELDABLE IN TORSION, MEANS FOR ANGULARLY ADJUSTING ONE PORTION OF THE SHAFT WITH RESPECT TO ANOTHER PORTION INCLUDING PORTIONS AT WHICH SAID SHAFT MAY BE ENGAGED TO ENABLE SAID CONTROL PORTIONS TO BE ROTATED TO PERMANENTLY DISTOR SAID YIELDABLE PORTION. 